Height and weight are often used in epidemiological studies as possible predictors of disease outcomes. If the people in the study are assessed in a clinic, heights and weights are usually measured directly. However, if the people are interviewed at home or by mail, a person's self-reported height and weight are often used instead. Suppose that we conduct a study on 10 people to test the comparability of these two methods. Data from these 10 people were obtained using both methods on each person. What is the criterion for the comparison? What is the null hypothesis? Should a two- or a one-sided test be used here?